Which statement is true under the ideal gas assumptions?

• A. Gas particles move constantly and randomly
• B. Gas particles have strong intermolecular forces
• C. Collisions are inelastic
• D. The volume occupied by the molecules is significant

Answer: (A)

This question hinges on the kinetic theory assumptions that define an ideal gas. Under these assumptions, gas particles are in constant, random motion inside a container. They collide with the container walls and with each other in perfectly elastic collisions, so kinetic energy is conserved in collisions. Intermolecular forces are negligible, meaning there are no strong attractions or repulsions between molecules. The molecules themselves are treated as point particles, so the volume they occupy is negligible compared with the volume of the container.

Because of these ideas, the statement about constant and random motion is the one that fits the ideal gas model. The other statements contradict the model: there are no strong intermolecular forces; collisions are not inelastic; and the volume of the molecules is not significant relative to the container.